下等生物の光感覚の比較生理

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タイトル別名
  • Photoreception in lower organisms
  • カトウ セイブツ ノ コウカンカク ノ ヒカク セイリ

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1. Photosensory transduction in aneural systems was exemplified by non-flagellar propulsive gliding of trichomes of cyanophytes and by movements of Euglena induced by flagellar activity. The intracellular transduction mechanism of the latter was schematized by modifying the Diehn's model10) (Fig. 1).<BR>2. Dermal photosensitivity is involved in various types of on- and off-reflexes and of tactic and kinetic movements. In a number of animals, dermal and ocellar photoreception often co-exists and the work of Gwilliam37) on Nereis was considered to be a good example (Fig. 2 ).<BR>3. Neuronal photosensitivity functions in inducing reflex movements (crayfish and sea-urchins, Fig. 3), in entraining the circadian rhythm in locomotor and some nervous activities (Aplysia) and in facilitating the conduction of excitation evoked by tactile stimuli (Onchidium). The work of Brown and Brown59) on the giant neurone of Aplysia was discussed in relation to the Ca++ theory on the photoexcitation mechanism.<BR>4. Differentiation of photoreceptive organs may be correlated to development of mass potentials (ERG) at on and off. Poorly organized ocelli produce no detectable ERG. When more differentiated, ERG's consisting of multiple components appear at on (Fig. 4). The sustaining level in ERG's during illumination as seen in higher animals seems to require a more elaborate organization of the receptive layer (Fig. 5).<BR>5. Differentiation of photosensory cells is manifest as enlargement of the photoreceptive surface which is achieved at first by utilization of ciliary shafts and then by formation of microvilli. A change over from motile to non-motile cilium appears to be associated with the first step of elaboration as a photosensory cell. A tentative scheme relating morphologically dermal, neuronal and ocellar photoreceptions was presented. (Fig. 7).

収録刊行物

  • 生物物理

    生物物理 14 (4), 157-170, 1974

    一般社団法人 日本生物物理学会

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